During downlink transmission of an LTE (Long Term Evolution) communications system, an eNB (evolved base station) generally performs data transmission in a unit of subframe, where a subframe length is 1 millisecond, and one subframe includes a physical downlink shared channel (PDSCH for short) region and a physical downlink control channel (PDCCH for short) region. The PDSCH is used to carry data sent by the eNB to user equipment, and the PDCCH is used to carry resource allocation information sent by the eNB to user equipment. To properly use a physical resource of the PDCCH region, the eNB divides the PDCCH region into different subregions, where each subregion is a search space.
The eNB sends the resource allocation information to the user equipment by using a PDCCH in the search space. To receive resource allocation information sent in the search space by the eNB, the user equipment performs blind detection on the PDCCH in the search space. If the user equipment detects the resource allocation information sent by the eNB to the user equipment, the user equipment receives the resource allocation information.
In the search space, one PDCCH carries one piece of resource allocation information, and because lengths of different resource allocation information are not completely the same, quantities of physical resource units occupied by different PDCCHs that carry different resource allocation information, that is, scheduling control channel lengths are also not completely the same. Therefore, when performing blind detection, the user equipment separately performs blind detection in the search space according to various possible scheduling control channel lengths, which causes low blind detection efficiency and excessively much power consumption of the user equipment.